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For example, the twin operation may be reflection across a plane that is not a symmetry plane of the single crystal. [ 1 ] [ 2 ] On the microscopic level, the twin boundary is characterized by a set of atomic positions in the crystal lattice that are shared between the two orientations.
They are formed by a local deviation of the stacking sequence of layers in a crystal. An example would be the ABABCABAB stacking sequence. A twin boundary is a defect that introduces a plane of mirror symmetry in the ordering of a crystal. For example, in cubic close-packed crystals, the stacking sequence of a twin boundary would be ABCABCBACBA.
The classical Stefan problem aims to describe the evolution of the boundary between two phases of a material undergoing a phase change, for example the melting of a solid, such as ice to water. This is accomplished by solving heat equations in both regions, subject to given boundary and initial conditions. At the interface between the phases ...
A topological defect is perhaps the simplest way of understanding the general idea: it is a soliton that occurs in a crystalline lattice, typically studied in the context of solid state physics and materials science. The prototypical example is the screw dislocation; it is a dislocation of the lattice that spirals around. It can be moved from ...
For example, in an ordered AB alloy, if an A atom occupies the site usually occupied by a B atom, a type of crystallographic point defect called an antisite defect is formed. If an entire region of the crystal is translated such that every atom in a region of the plane of atoms sits on its antisite, an antiphase domain is formed.
The Kirkendall effect is the motion of the interface between two metals that occurs due to the difference in diffusion rates of the metal atoms. The effect can be observed, for example, by placing insoluble markers at the interface between a pure metal and an alloy containing that metal, and heating to a temperature where atomic diffusion is reasonable for the given timescale; the boundary ...
The box was actually a climate-controlled crib designed for comfort and protection, and the young psychologist was merely testing his theory that environment controls behavior. NOVA portrays the life of this famous behavioral psychologist now in his 70's and living quietly in Cambridge as Emeritus professor of Psychology at Harvard University.
Specifically, an SU(2) Chern–Simons theory describes the simplest non-abelian anyonic model of a TQC, the Yang–Lee–Fibonacci model. [2] [3] The dynamics of Chern–Simons theory on the 2-dimensional boundary of a 3-manifold is closely related to fusion rules and conformal blocks in conformal field theory, and in particular WZW theory. [1] [4]